Setting bolts longer than the available height is usually done by drilling with extension rods, manually bending the bolt before inserting it in the hole and straightening it when the first half is in the hole.
In order to mechanize these operations, several flexible drill machines have been tested, but the drill rod is flexible only before being submitted to torque and thrust. This means a cumbersome drive is set at the hole orifice.
Machines to bend and insert bolts have also been developed but they are not adapted to resin bolts. The driving head is also complex and cumbersome. Therefore, they would not permit bolting ahead of the working face, which is the key to safety improvement.